The present invention is generally directed to fuel cells and more specifically to solid oxide fuel cells and their operation.
Fuel cells are electrochemical devices which can convert energy stored in fuels to electrical energy with high efficiencies. A solid oxide fuel cell (SOFC) generates electrical energy and reactant product from fuel and oxidizer. The SOFC contains a ceramic electrolyte, a negative or fuel electrode and a positive or oxygen electrode. The electrolyte is usually a doped zirconia ceramic. The negative or fuel electrode (referred hereto as the “anode” electrode) may be made from a cermet, such as a nickel-yttria stabilized zirconia (“YSZ”) cermet. The positive or oxygen electrode (referred hereto as the “cathode” electrode) is usually made of a ceramic perovskite material, such as lanthanum strontium manganite (“LSM”) having a formula (La,Sr)MnO3 or lanthanum strontium cobaltite (“LSCo”) having a formula (La,Sr)CoO3. Furthermore, contact layers, such as a Ni or nickel oxide anode contact layer and an LSM or LSCo cathode contact layer may be formed on the anode and cathode electrodes, respectively. The SOFC is usually part of a system which includes a plurality of electrically connected fuel cells and other components, such as gas separator/interconnect plates, seals and electrical contacts. Each gas separator/interconnect plate contacts the electrode and/or current collector layer of adjacent fuel cells. One draw back of SOFCs is their degradation over time.